Soybeans are considered one of the optimum sources of supplemental protein fed to livestock today. Raw soybeans, however, cannot be fed to livestock and consequently, raw soybeans must be treated in order to make them suitable feed supplements. The reason soybeans cannot be fed in the raw state is because proteolytic inhibiting substances are present in the raw soybeans. The presence of these inhibiting substances requires that the raw soybeans be cooked or heated in order to destroy harmful urease enzymes and trypsin inhibitors. These substances in the raw soybeans have a retarding effect upon the growth of livestock and they can actually prevent proper utilization of the protein supplementation provided by the soybean feed material. Care must be taken in the heating process, however, because even though the heating is required to destroy the trypsin inhibitors, improper cooking will result in damage to the protein product itself.
If excessive heat is applied during the processing, the feeding value may be low because some of the amino acids will become unavailable for use in the feed product. If raw soybean is taken through a treating process and left undercooked, that is, not enough heat is applied, urease activity will be high and the trypsin inhibitors will not be destroyed.
Devices for heating or steaming grains, seeds, beans and other agricultural products including soybeans have been known for years. Indeed, some of the very earliest United States Patents are directed to steaming devices: Fisher, U.S. Pat. No. 129,018 (1872); Fisher, U.S. Pat. No. 129,544 (1872); Jewell, U.S. Pat. No. 484,099 (1892); Shamp, U.S. Pat. No. 493,225 (1893); Howie, U.S. Pat. No. 552,127 (1895); Griess, U.S. Pat. No. 558,065 (1896); Quitzo, U.S. Pat. No. 559,603 (1896); Blackburn et al., U.S. Pat. No. 571,638 (1896); Quitzo, U.S. Pat. No. 578,523 (1897); Provost, U.S. Pat. No. 785,119 (1905); Provost, U.S. Pat. No. 971,559 (1910); and more recently, Brandt et al., U.S. Pat. No. 3,721,018 (1973). A number of these patents, such as the two Fisher patents, the Blackburn et al. patent, and the Brandt patent include a steam chamber in which steam is provided into the chamber by means of a perforated pipe. In the Fisher U.S. Pat. No. '018 patent a steam coil is provided within a lower chamber and in the Fisher U.S. Pat. No. '544 patent, a coil of steam pipes is provided at the base of an elevated hopper. Both of the patents also disclose compartments which expand outwardly toward the bottom thereof. In Brandt et al. U.S. Pat. No. '018, a lower compartment well below the introduction of the steam is divided into a plurality of compartments which are inclined to form a tapering rectangluar gridwork or baffle to prevent channeling of the grain treated therein. These channels taper toward the bottom in conformity with the cross-sectional shape of the lower section. The other patents, such as Shamp U.S. Pat. No. '225 and Howie U.S. Pat. No. '127 provide steam through the walls of a chamber which contains the matter being treated. Blackburn et al. U.S. Pat. No. '638 injects steam through a plurality of steam pipes over which are positioned conical spreaders to disperse the material being treated. Provost U.S. Pat. No. '119 also provides a conical spreader for dispersing the material. The other patents also disclose various shapes and configurations of steaming apparatuses.
To this day, the configuration and operation of steaming chambers has changed very little from the steam chambers of nearly 100 years ago. Basically, steam chambers comprise single chambers with a plurality of pipes to inject steam into the chamber at one or more locations or steam is injected through the wall of the chamber. Diverter tents are typically positioned over the steam inlet pipes in order to divert the product being treated as well as prevent the product from clogging the steam pipes, and because grains such as corn and wheat do not have to be treated for any particularly long length of time, the lengths of the prior steam compartments are generally less than 10 feet.
Furthermore, because these prior steam chambers are designed for treatment of grain products which have no particularly stringent treatment requirements, they have not taken into consideration the very special requirements necessary for processing soybeans. One of these requirments is that the soybeans be heated for a required amount of the, oftentimes 45-60 minutes, to deactivate the various harmful protein inhibitors. Another requirement which is overlooked by these prior steam chambers is a requirement that the steam chamber remain essencially unobstructed or free of diverters and steam pipes for the processing of soybeans. These obstructions may not interfere with the steam treatment of certain smaller grains, but these obstructions cause channeling and disruption of uniform flow of soybeans passing therethrough. Soybeans have different flow characteristics which are easily disrupted by these obstructions. Oftentimes, obstructions such as tents over the steam pipes and the mere presence of the steam pipes interspersed throughout the steam chamber will cause the soybeans passing downward through the chamber to reverse their direction of flow and cause the soybeans to channel or become stalled in a swirling motion as a continuous path. When this happens, flow through the center of the chamber is disrupted and incoming soybeans will rush rapidly along the walls of the chamber and leave the chamber in far less than the time required to deactivate the harmful inhibitors.
Still further, many of the steam chambers which are currently available are designed for use only on a batch basis; that is, they are filled with product, steam is injected and all of the steamed product is removed prior to introduction of another supply of product to be treated. The concept of an apparatus for continuous steam treatment of a soybean product does not seem to have been developed.